1. Field of the Invention
The subject invention relates to an increased efficiency counter-rotating electric motor and to suitable marine-vehicle propulsion systems and uses for the subject motor which has an improved efficiency of operation over traditional motors. When utilized on a typical fishing boat, this type of marine-vehicle propulsion system is frequently termed a “trolling” motor. More specifically, the subject invention utilizes a counter-rotating electric motor in which both an armature/rotor and a stator/field magnets rotate in opposite directions during operation. Generally, the subject motor is suspended by support means, wherein an armature shaft or axle is attached to and extends from the armature of the motor and a stator shaft or axle is attached to and extends from the stator of the subject motor. Included is a properly configured centrifugal-force-balancing means that is mandated by the rotating stator. As indicated, both the armature and the stator rotate, in opposite directions, thereby minimizing the creation of heat during operation and accessing torsional forces normally lost by utilizing a traditional motor in which the stator is fixed within the motor housing.
2. Description of Related Art
For a traditional motor, the outside/surrounding motor housing is stationary, as is the stator/field magnets within the housing. The stator is usually affixed to the housing. An internal armature/rotor is attached to a shaft or axle that rotates during operation (in some versions of a standard motor the rotor may be termed the armature). Thus, the armature shaft/axle extends out from the stationary motor housing and rotates when electrical current is applied to the motor (the armature/rotor rotates within the stationary stator/field magnets). The history of traditional electric motors is extensive and one version is found at www.sparkmuseum.com/MOTORS.HTM.
A counter-rotating electric motor is described in related U.S. Pat. Nos. 2,431,255, 2,456,993, and 2,462,182. The disclosed motor was to be used in torpedo propulsion systems in which a coaxial propeller assembly drove separate propellers in opposite directions to aid in keeping the torpedo traveling in a desired direction. Clearly, the operational lifetime of such a motor is extremely limited, given its destruction upon hitting a target. To eliminate necessary centrifugal/centripetal influenced commutator-to-brush contact breaks created while the stator is rotating (normally the stator is not rotating so a constant resilient means or spring simply forces a brush inward and towards the center of rotation, thereby contacting the commutator for the required electrical communication, but rotation of the stator causes the brushes to “float” away from the commutator), the device contained a “radial commutator” (a disk extending outwardly from the axis of rotation) and contact brushes directed parallel to the axis of rotation. This radial commutator/brush design is complex, not easily fabricated, and, thus, expensive to manufacture.
U.S. Pat. No. 4,056,746 presents a counter rotation electric motor that is quite similar to the design present immediately above. Once again a radial commutator/brush design is utilized in the operation of the device.
A DC rotary machine is related in U.S. Pat. No. 4,259,604. The commutator/brush design in this device is very simplistic and is not created to operate at high rotational velocities. Typically, the motor is used in a machine such as a tape recorder, VTR, and the like that need low rotational speeds. The commutator is of standard cylindrical design and the brushes are contacted in a permanent fashion against the commutator bars.
A dual rotary AC generator is described in U.S. Pat. No. 5,089,734. This disclosure presents, basically, a motor run in reverse, thereby becoming a generator in which both the magnetic field and armature rotate in opposite directions. Unfortunately, the manner in which the device receives or delivers electricity is not related, nor are any internal electrical components described.
U.S. Patent Publication No.: 2006/0163963 discloses a counter rotating generator. Once again, a radially disposed set of disks are utilized in the commutator/brush design. In this case, the slip rings have a relatively large diameter (which is claimed to decrease heat production) and contact brushes in a continual manner, with constant force, regardless of rotational speed. Additionally, the described generator is used in relatively slow RPM situations in which the wind or manual cranking are utilized as the driving forces, unlike the subject invention that may be operated from relatively low to relatively high RPM values.